1) Field of the Invention
This invention generally relates to methods for shaping and forming malleable sheet material (e.g., metal sheet), and, more particularly, to a method for bending sheet metal along either straight or curved score lines.
2) Description of the Prior Art
Sheet metal is a commonly used material for a multitude of applications including housings and casings, interior and exterior structures, and various covers and supports. Stock sheet metal is typically supplied to manufactures in the form of flat sheets or rolls of flat stock. The manufacturer uses the stock metal sheet and cuts, shapes, and bends the metal, as necessary, to manufacture various products.
Bending sheet metal is conventionally accomplished using either hand tools and/or forms, or bending machines including press and box brakes, and roll embossing machines, depending on the type of bend being performed and the desired results. Although sheet metal may be bent along a line which is either straight or curved, bending along curved lines requires specialized tooling to support the metal sheet on one side of the bending line, and also encourage the metal located on the opposing side of the bending line to bend along the curved line. Depending on the specific shape of the bending line, heat may be necessary to discourage distortion. Not only is this curve-line tooling costly and time-consuming, customizing it to the particular bend, the resulting tooling is also unique to each specific curve, and therefore may have a limited usefulness (i.e., only useful in bending a piece of metal along one specific shape curve).
Computers are used to control many metal-forming and metal cutting machines quickly and accurately. One such computer-controlled machine is a laser cutter wherein a laser beam of high energy is controlled by a computer and guided along one surface of metal sheet. The laser energy quickly and accurately cuts or etches the metal sheet, as controlled by the computer and as prescribed by software. Another type of cutting and etching machine uses a powerful stream of water, usually including an abrasive. The resulting water-jet is carefully controlled to abrade through metal sheet. The water-j et system allows for accurate cut lines or etched lines having a prescribed depth. Another software-driven technique involves scribing or milling the metal with a hard cutting tool driven by a computer.
It is an object of the invention to provide a method for bending sheet metal, which overcomes the deficiencies of the prior art.
Another object of the invention is to provide such a method for bending sheet metal wherein the bending line is curved in one or more directions.
Another object of the invention is to provide a method for bending sheet metal along a curved bending line wherein bending stress to the metal is minimized and controlled to minimize metal fatigue and distortion.
Another object of the invention is to provide a method for bending sheet metal to form 3-dimensional structures for architecture.
Accordingly, a method for bending sheet metal is disclosed which includes introducing to the sheet metal thinned regions which are positioned either along or immediately adjacent to the bending line. These thinned regions allow the metal to be easily bent along the bending line using conventional hand tools or non specialized machines. The thinned regions are preferably shaped as slots cutting through the metal and having a specific width, length, end shape, and spacing from each adjacent slot. In some instances, the slots have a depth into the metal sheet. In other instances, the thinned regions with a depth are continuous.
According to one embodiment of the invention, each slot is cut through the entire thickness of the metal sheet. This embodiment is particularly useful for building structures on an architectural scale. Other related embodiments require that the slots be only partially cut or etched, thereby having a depth that is less than the thickness of the metal sheet. Etched slots of this kind are particularly useful for thinner sheet metals. The thinned regions may be any appropriate shape depending on the shape of the bend, the type of metal, the thickness of the metal, the ductility of the metal, the angle of the final bend, and the application of the metal (e.g., is the metal structure intended to be load bearing, etc).
According to a second embodiment, two generally parallel sets of thinned regions are formed adjacent and generally parallel to the bending line. Each set may include different types of thinned regions to encourage bending of the metal along the bending line. The thinned regions are preferably slots that cut through the metal sheet. In a preferred application of this second embodiment, the two sets of slots are staggered or offset with respect to each other. This embodiment is also particularly useful for building structures on an architectural scale.
According to a third embodiment, a continuous thinned region that has a depth less than the thickness of the metal is used instead of interrupted aligned or staggered slots. This has aesthetic as well as practical advantages since there are no cut regions that need to filled in.
The thinned regions may be introduced into the metal sheet using conventional machines or computer-driven machines such as a laser cutting machine or a water jet-cutting machine or other softwareware-driven devices which enable grooving or selective weakening of metal through other means. These machines are capable of either cutting completely through the metal sheet, or just etching the thinned regions only partially through the metal sheet, as required. Also, these machines are capable of accurately cutting along lines which may be straight and/or curved.
While specific embodiments have been described herein, it will be clear to those skilled in the art that various modifications and changes may be made without departing from the spirit and scope of the present invention.